A data storage device is an electronic device for writing and/or reading electronic data. The data storage device can be implemented as volatile memory, such as random-access memory (RAM), which conventionally require power to maintain its stored information or non-volatile memory, such as read-only memory (ROM), which can maintain its stored information even when not powered. RAM can be implemented in a dynamic random-access memory (DRAM), a static random-access memory (SRAM), and/or a non-volatile random-access memory (NVRAM), often referred to as a flash memory, configuration. The electronic data can be written into and/or read from an array of memory cells which can be accessible through various control lines.
Magnetic Random Access Memory (MRAM) and Resistive Random Access Memory (RRAM) are two types of recently developed memory devices. MRAM and RRAM are applicable for embedded memory, DRAM replacement, flash replacement, among other applications. MRAM and RRAM devices are inherently sensitive to process variations during device fabrication. Therefore, memory performance variations during testing are observed from die-to-die across a semiconductor wafer, and even block-to-block within a single integrated circuit (IC) die. Different die at different wafer locations (e.g. center die vs. edge die) and different blocks of a single large MRAM OR RRAM IC can often have very different read/write windows, and fail the performance test of read/write window margin at a very high rate, which can limit the usefulness of the MRAM and the RRAM devices.